New to Porting

[mdavlee]

Use carbide in 1/4”. They’re a lot tougher than the small ones. I never had them slip on me. I pushed hard enough to bend or break the little mandrels though

 

[Nutball]

You've never had the sand paper rolls slip? I'm using 1/4" mandrel, but I guess you could break a 1/8" one, it wouldn't be easy at all though.

I guess I'll try a carbide. Any speed suggestions for cutting steel?

The gasket was miserable to work on. That paste like metal stuff easily make a mess, but doesn't clean up well, and doesn't cut off with the rest of the gasket. It even peels back in the opposite direction the cutter is going. Crazy stuff.

 

[mdavlee]

They come apart normally before slipping. I twist them on holding the chuck so they sort of thread on the mandrel.

 

[huskihl]

I have a few American made 1/4' fine double cut carbides for the die grinder in cylinder and flame shapes for mufflers.

 

[Billy Currie]

One thing I have recently started doing is using round chain files to port with. I will first cut a notch in the ports giving me a target depth and height with a die grinder. Then finish with files. Sure it takes longer, but I can smooth the entire length of an intake or exhaust port with no bumps, ripples, or low spots. I tried this when I was cutting too much too fast. I started loosing control of what I wanted.

 

[Nutball]

I see now how you can drive the screw on the mandrel into the sanding rolls. I thought the screw part was for the fuzzy abrasive things.

I found that some green grinding discs, likely silicon carbide, were the fastest at grinding steel over a burr, sand roll, and pink grind stone. Still it took like 1.5hrs to open the rear of the muffler, and 4 stones.

 

[Nutball]

I got a compression tester. Only problem is, how do you test over 170psi in a 90cc saw without hurting yourself? That's where I couldn't pull any more on my 2188. The way I figure it with simple numbers: 2" piston, 3"sq of surface area with 200psi on it = 600lbs of force. If the starter is the same diameter as the crank, then you're pulling 600lbs. Do you guys use a drill for test cranking high compression big saws? I'd think that would undo the flywheel nut.

 

[Deets066]

Gotta put a little M.A.N. On the starter rope

 

[Deets066]

You could retard the timing to test compression then advance afterward.

 

[srcarr52]

I see now how you can drive the screw on the mandrel into the sanding rolls. I thought the screw part was for the fuzzy abrasive things.

I found that some green grinding discs, likely silicon carbide, were the fastest at grinding steel over a burr, sand roll, and pink grind stone. Still it took like 1.5hrs to open the rear of the muffler, and 4 stones.

A carbide burr would take only a few minutes to open up a muffler flange.

 

[Nutball]

It sure was taking a long time for me. This flange was a good 3/16" thick, and I needed to take 1/16-1/8" off of it.

 

[Deets066]

Yup, 1/4” shank, carbide burr is what I use on mufflers. Bout 10 minutes

 

[Nutball]

Maybe I didn't push hard enough, or use an aggressive enough burr, or use enough rpm. I used a double cut at slow to mid rpm with light pressure.

 

[Deets066]

Maybe I didn't push hard enough, or use an aggressive enough burr, or use enough rpm. I used a double cut at slow to mid rpm with light pressure.

Oil it and full rpm, adjust pressure accordingly

 

[mdavlee]

I got a compression tester. Only problem is, how do you test over 170psi in a 90cc saw without hurting yourself? That's where I couldn't pull any more on my 2188. The way I figure it with simple numbers: 2" piston, 3"sq of surface area with 200psi on it = 600lbs of force. If the starter is the same diameter as the crank, then you're pulling 600lbs. Do you guys use a drill for test cranking high compression big saws? I'd think that would undo the flywheel nut.

Pull harder[emoji51] worst I ever did was a 62mm 088. 2188/390 was never a problem to about 220.

 

[huskihl]

I got a compression tester. Only problem is, how do you test over 170psi in a 90cc saw without hurting yourself? That's where I couldn't pull any more on my 2188. The way I figure it with simple numbers: 2" piston, 3"sq of surface area with 200psi on it = 600lbs of force. If the starter is the same diameter as the crank, then you're pulling 600lbs. Do you guys use a drill for test cranking high compression big saws? I'd think that would undo the flywheel nut.

Pull harder[emoji51] worst I ever did was a 62mm 088. 2188/390 was never a problem to about 220.

A 24" bar mounted up might help tame it down

 

[beaglebriar]

Tried to fire up one of the 372's the other morning in single digit temps. It would pop the decomp shut after about one revolution. I don't remember where the compression ended up on that one but it's probably 210+

Usually pulls over easy but it didn't like the cold temps. It did start when I quit being a sissy about it...

 

[huskihl]

Tried to fire up one of the 372's the other morning in single digit temps. It would pop the decomp shut after about one revolution. I don't remember where the compression ended up on that one but it's probably 210+

Usually pulls over easy but it didn't like the cold temps. It did start when I quit being a sissy about it...

A decomp from a 390 doesn't pop out as easily. So ya know

 

[beaglebriar]

A decomp from a 390 doesn't pop out as easily. So ya know

I think that's what's in it...hell I never use the decomp but I needed it Sunday.

 

[Stump Shot]

Tried to fire up one of the 372's the other morning in single digit temps. It would pop the decomp shut after about one revolution. I don't remember where the compression ended up on that one but it's probably 210+

Usually pulls over easy but it didn't like the cold temps. It did start when I quit being a sissy about it...

Did the same thing with my 272, gave up and grabbed a different saw as I didn't want to wait to warm it up.

Stupid pop ups. Lol